Two types of immunity occur in humans:
1. Innate Immunity
2. Acquired Immunity
Innate immunity is the natural defense present since birth, whereas acquired immunity is developed after exposure to pathogens through infections or vaccinations.
(b) Order of the differential equation: $ 5x^3 \frac{d^3y}{dx^3} - 3\left(\frac{dy}{dx}\right)^2 + \left(\frac{d^2y}{dx^2}\right)^4 + y = 0 $